Since 2021 the FCC no longer gives amateur stations a categorical exemption from its radio frequency exposure limits. Every licensee must determine that their station complies, keep the reasoning where they can produce it, and redo it whenever the station changes materially. Nothing is filed with the FCC — but if a complaint reaches the Enforcement Bureau, "I never looked at it" is not an answer.
What the limits actually are
The rules set maximum permissible exposure (MPE) in terms of power density and averaged over time, and they are stricter in two ways people find surprising:
- The general population limit is more restrictive than the occupational one. You and your
- The most restrictive frequencies are in the VHF range, roughly 30–300 MHz, because the human
- Averaging times are 6 minutes (occupational) and 30 minutes (general population), so duty cycle
family may fall under either depending on who knows what: occupational limits apply only to people who are aware of the exposure and can act to limit it.
body is resonant there. A 50 W 2 m station needs more thought than a 100 W 80 m station.
matters enormously. SSB at a normal speech rhythm is a small fraction of your rated output; FM, digital modes such as FT8, and a keyed carrier are not.
Doing the evaluation
For nearly every amateur station the arithmetic is a worst-case calculation, not a measurement:
- Take the power reaching the antenna (rated output minus feedline loss).
- Multiply by the antenna gain in the direction that matters, and by your mode and on-air duty
- Compare the resulting power density at the closest distance a person can get to the limit for
cycle.
that band.
The ARRL's RF exposure calculator and the FCC's OET Bulletin 65 Supplement B both do this for you; so does the exposure worksheet in most study guides. Print the result, note the date, the band, the power, the antenna and the distances, and keep it with your license.
Fixing a station that does not pass
- Move the antenna: distance is the cheapest control there is, and power density falls with the
- Reduce power, or reduce it only on the band that fails.
- Change the pattern — point the main lobe away from occupied space, or raise the antenna so its
- Restrict access while transmitting: a fence, a locked room, or simply not transmitting when
square of it.
lobe clears people.
someone is on the deck under the beam.
The rest of station safety
RF exposure gets the paperwork, but it is not what hurts amateurs. Take at least as seriously:
- Line voltage and amplifier supplies. A tube amplifier holds a lethal charge after it is
- Falls and power lines. No antenna is worth touching a utility line — assume any wire you did
- RF burns. An end-fed wire at head height carries high voltage at its ends. Put those ends
- Batteries. Lithium iron phosphate and lead-acid packs both deliver enough current to weld a
- Lightning. Bond everything to a single ground point and disconnect when a storm approaches;
unplugged. Bleeder resistors fail; check with a meter before you reach in.
not install is live, and plan the fall path before you raise anything. See towers and masts.
where nobody can reach them.
dropped wrench; fuse every battery lead at the battery.